The present invention relates generally to an air brake hose coupling member for a rail car. More particularly, the invention relates to an improved air brake hose coupling member having a pawl for engaging another coupling member automatically and for preventing undesired rotational decoupling of the members when the pawl is in a closed position.
Railroad cars use rigid and flexible air hoses, which extend along and between railroad cars, for operation of the pneumatic brake system. Coupling members are attached to each end of the flexible hoses between the cars for detachably connecting the hoses together when individual railroad cars are joined to form a train. These couplings are designed and manufactured to meet the requirements of the Association of American Railroads and are, generally, similar so as to be compatible and interchangeable with those of other manufacturers.
Normally, each coupling member is suspended from the end of a car and hangs a short distance above the railroad tracks. As is well known in the art, the couplings are joined together by pulling the air hoses from adjacent cars toward each other and pushing the seating gasket on each coupling member into an aligned and abutting relationship. The coupling members are then rotated to interengage the mating flanges and lugs that extend from the coupling members.
Often, these coupling operations are done at night and/or in adverse weather conditions. If properly performed, the coupling operation results in a sealed, fluid passage between air hoses on adjacent rail cars, whereby the air pressure in the pneumatic hose line maintains the brakes of all the individual cars in a xe2x80x9creleasedxe2x80x9d position. Any undesired decoupling of the members will result in a loss of air pressure, which will cause the brakes in all of the cars to go to an xe2x80x9cappliedxe2x80x9d or braking position, resulting in the sudden stopping of the train with the subsequent delay, inconvenience and expense, as well as the chance of accidents.
However, occasionally, coupled members can become uncoupled prematurely. This occurs, for instance, when they are struck or pushed up by a raised object, or the like, lying between the railroad tracks. That action can cause the members to rotate in an uncoupling direction, resulting in the undesirable emergency stopping of the train. It is, thus, desirous to avoid undesired rotational decoupling of the members.
Several types of locking devices have been devised for known coupling members to prevent undesired uncoupling, such as shown in U.S. Pat. Nos.: 3,892,431; 3,879,066; 5,388,864; and 5,971,442. Although these types of locking devices do reduce the accidental rotational uncoupling of the coupling members, all of them require the manual manipulation of the coupling member and manual operation of some part of the locking mechanism in order to have one coupling member engage, rotate, couple and rotationally lock with another member. That, in turn, requires a certain dexterity and effort in normal and adverse conditions to both engage and rotationally lock coupling members.
Therefore, a need exists for an improved air brake hose coupling member that does not require manual manipulation of the coupling member locking mechanism to prevent undesired rotational decoupling of two members.
The present invention has a locking mechanism that is automatically engaged when two coupling members are brought into abutting relationship and rotated in a coupling direction.
The present invention relates to an improved air brake hose coupling member for a rail car. The coupling member has a generally tubular body with a longitudinal axis and an inner coupling face at a first end of the body. The coupling face is aligned generally in a plane parallel to the longitudinal axis and extends around an air passage. The coupling member also includes a shank at a second end of the body that is adapted to be connected to an air brake hose. The coupling member also has an arcuate locking lug projecting outwardly from the first end of the body and has an L-shaped annular flange. The coupling member further includes a pawl that is pivotally mounted on the coupling member. The pawl has a ramp for engaging another coupling member and for causing the pawl to be raised to an opened or unlocking position automatically during coupling of the members. The axis of rotation of the pawl is in a plane substantially parallel to the inner coupling face and substantially parallel to the longitudinal axis of the tubular body. The coupling member also has a biasing element that causes the pawl to drop down into a closed or locking position after the coupling of the members is complete.
The locking lug and L-shaped annular flange are adapted to engage with the L-shaped annular flange and locking lug, respectively, of another coupling member. That couples the members together when the inner coupling faces of the two coupling members are placed in an abutting relationship substantially along their entire inner coupling faces and are rotated with respect to each other. When the members are fully coupled and the pawl automatically is in a closed position. The pawl prevents undesired rotational decoupling of the members when coupled members are rotated oppositely with respect to one another in a decoupling direction.
A ramp or initial cam surface on the pawl may extend at an acute angle (for instance, approximately in the range of 35-55 degrees) downward from a plane of a top surface of the arcuate locking lug to initially engage another coupling member. The pawl may further include a riding surface, adjacent and generally at an acute or close to right angle, for instance, in the range of approximately 70-90xc2x0 to the initial cam surface, that extends in a plane that is substantially parallel to the plane of the top surface of the pawl. The pawl may further include a transition surface adjacent to both the initial cam surface and the riding surface to assist the pawl in moving from its initial contact position on the ramp to an engaging or riding position on the L-shaped flange of another coupling member.
The pawl may also include one or more locking surfaces to trap or stop the L-shaped flange of another coupling member. The at least one locking surface extends downward in a plane substantially perpendicular to the plane of the top surface of the pawl. The pawl may further include extension surfaces to cause the pawl, when mounted on the coupling member, to be so positioned such that the locking surface or surfaces are able to trap or stop another coupling member from uncoupling.
The pawl may be designed to fracture at a predetermined location such that the remaining portion of the pawl mounted on the coupling member may be without any locking surfaces but still leave the member able to function as a coupling member by allowing desired or intentional rotational decoupling. That functioning coupling member may have no sharp parts hanging on or from the pawl, thereby preventing injury while allowing desired rotational decoupling. The pawl may be weighted so as to fall into the locking position, even if the biasing element fails. The pawl may also be adapted to be raised to an opened or unlocking position manually and to be lowered to a closed or locking position manually.
The pawl may further include an opening adapted to receive a pin to mount the pawl on the coupling member, and that opening is in a ball-shaped end. When the pawl is raised or lowered, it pivots about an axis defined by the pin mounted in a hole on the coupling member. The coupling member may also include a pin for pivotally mounting the pawl to the coupling member. The coupling member may further include one or more holes that are adapted to receive the pin and an end of the pawl.
The biasing element may be a torsion spring, which may be detachably connected to the pawl, pin and coupling member.
Existing non-locking coupling members may also be modified or retrofitted with the locking element, or pawl, of the present invention. The method of doing this is by drilling one or more holes in the non-locking coupling member, and then mounting the pawl in one of the holes such that the pawl will rotate in a plane substantially parallel to the inner coupling face and substantially parallel to the longitudinal axis of the body.